Cellophane laminated with styreneisobutylene copolymer



July 22, 1952 o. c. SLOTTERBECK ET AL 2,604,423

CELLOPHANE LAMINATED WITH STYRENE-ISOBU'IYLENE COPLYMER Filed oct. e, 1944 FI .-1 [rf/' 2 poul PLAsTlo i) HC PLASTIC,

Fra-S 4 F1a-10 f Ober' C. 'Zaerbeck ZJZZzam H. 5ml/erp 'Javentor David nq Patented July 2 2, 1952 UNrrEvf-STATES 'PATENT l CELLOPHANE LAMINATED WITH STYRENE- Y- YISOBUTYLENE COPOLYMER Ober C. Slotterbeck, Rahway, William H. Smyers,

' Westfield, and'David W. Young, Roselle, N. J.,

assignors' "to Standard Oil Development'Company,"a corporation of Delaware f Application October 6, 1944, Serial No. 557,506

, 1.1 This invention relates to novel products and to .preparation and "use thereof and more particularly it lrelates to the use of two different types oi high molecular weight orgnicplastics and various uses thereof particularly in the form of laminated sheet materials, especially suitable as a colorless Wrappi'ngrnaterial.

One of the vtwo primary materials used in making the products of this invention is a hydrocarbon copolymer 'of an olenic Icycliccompound with an alkene, as typifiedl by a styrene-isobutylene copolymer, andthe 'other primaryma'terial is an organic 'plasticnot only containing hydrogen and carbon butalso'containing Vat least one polar element, 'such as oxygen, nitrogen, chlorine Aand sulfur, 'and which for -brevity will be referred to as a polarfplastijc.. g

`The hydrocarbon `cnpolymersmaybe yprepared 'as disclosed in Patent2,274,749, such asv by copolymerizing rstyrene and isobutylene at temperatures below about C.. e. g.; -'20,C. 40 C., #80? C., 100 C. or even lower, in the presence 'ofa Friedel-Crafts catalystsuchas aluminum chloride,

boron fluoride, etc.,l preferably inthe presence of an inert volatile organicyliquid'serving as a solvent and/or refrigerant.,jy `The temperature may, Vfor instance, be C., 7-50 C.,' 'f90-C., #103 C. (the boiling point oil-liquid, ethylene), or'e'ven lower. By adjusting the proportions of the two raw materials, and the' temperature -ofr copolymerization, copolymers of desired hardness, melting point, plasticityy'etc.l may beobt'ained.

Instead ofisobutylene, other aliphatic oleiins may be used, preferably having more than two carbon atoms andpreierably iso-olefms having four to eight carbon atoms, such as -isopentene y(2mei'.hyl1bute`ne) or a normal lpentene obtained by dehydration, of secondarya-myl alcohol. Instead ci styrene,I other materials may-be yused suchv as alpha vmethyl styrene, para methyl styrene, indene,'te'rpenes, etc. Y Y Y The copolymerization is eflectedby mixing the two reactants,'wither-without aim-ritual solvent, such as ethylendpro'pan,butane, lmethyl chloride, refined naph'thm t., and their after cooling the vreactants"tothe desired low. temperature,

`addiilg'an active halide catalystsuch as boron ,solvent 'such as carbon disulfide, a low 'molecular weight sulfur-free saturated hydrocarbon, alowerl alkyl halide, e. g. kmethyl chloride or ethyl chloride or a mixture of methyl chloridewith lontane or propane, at or below theA boilingv point of the catalyst solvent, and then the catalyst solution cooled down, filtered and added to the reaction mixture. .Alternative catalysts include: A1C13.A1C12OH, A1Br3.AlBr2OI-I, AIBrzCLAlOC, A1B1Cl2.A1OBr, TC14.AlC12'OH; TOClz.TiC14, AlBr3.Br2.CS2, AlBr3,Br4.CS2, BF2-isopropyl alcohol complex, BF3 solution in ethylene, ,activated BFS catalyst in ethylene solution, activated BF2. catalyst in methyl chloride solution. Volatile solvents or diluents, e. g. propane, ethane, ethylene, methyl chloride, carbon'dioxide .(liquid or solid) etc. may also serve as internal orexternal Vrefrigerants to carry off theA liberated heat of polymerization. After completion of the copolymerization,

' residual catalyst may be hydrolized witljr alcohol,

soda.

'for example, isopropyl alcohol, or Water, orbo'th,

and removed'by washingxthe, product with water and preferably also wthl dilute i'aueousfe `ustic The resulting solidfcopolymer mayrange from a viscous fluid or a relatively'stii plasticl mass to a hard, resinous solid, depending upgon'the temperature of Y polymerization,l the yield of polymer obtained upon theactivefeedthe typ'ef and portions inVV which theV Astyrene and isobutylene have actually combined during copolymer'iz'ation lmay be determined'by interpolation of a'-'carbcn 'hydrogen analysis between the limits: 35 ,Y A

Carbon Hydrogen .Percent Per-cent Pure styrene 92.3 7.7 Pureisobutylene 85.7 l4.3

plasticity` of polymer product at room tempera- `ture being obtained "at'lower polymerization vteinperatures, e. 'gl -75'C. to --"1'03"`C`.v and-with lower content-'offcyclic reactantfefl gl 10% fto'lQF/, or on u the other' hand,with" relatively higher polymerization Vt'emperatiires suchas L40" C.v orl -20" C., and with higher proportion of and isobutylene will similarly be referred to for I' brevity as stybutene. The invention will be illustrated as applied particularly to stybutene, although it is not to be limited specifically thereto;

In referring to the stybutene, or more broadly the cycalkene, it is also intendedl to include not only such simple copolymers per se, but also such copolymers as modified by having various additives homogeneously compounded therewith as by milling or kneading or solution, as for instance,

polymeric condensation of diamino and dicarboxylic organic compounds such as the product marketed under the trade-name Nylon, olen polysulflde condensation products such as those 1 formed, by ,condensation,ofmethylene dichloride with sodiuni1tetrasu1'flde,j and marketed under the trade-name Thiokol, as well as halogenated derivatives of rubber such as chlorinated cyclicized natural rubber.

In preparing the polar plastics for use according to this invention, Various additives may be incorporatedthereinA by milling, kneading, solution, etc4.,.such`,as powdered inorganic or organic llers, pigments,- dyes, plasticizers, or hardenplasticizers and hardening agents, such as paraffn wax, petrolatum, beeswax, ceresin, synthetic waxy materials such as hydrogenated castor oil, high molecular Weight polyethylene, asphalt, tar, lanolin, zinc stearate, zinc dilinoleate, polybutene havin-g a molecular weight of at least 2,000, e. g. 15,000, 60,000, 100,000 or more, fatty oils such as linseed or other drying oils, polystyrene or other hardening agents such as a phenol rubber product made according to Patent 2,158,530, e. g. by treating beta-naphthol with rubber, as Well as other additives such as clay, carbon black or other fillers, pigment dyes, antioxidants suchas di-ortho-tertiary butyl derivatives of para cresol, tertiary. butyl catechol, pheny beta-naphthylamine, hydroquinone, as Well as ultraviolet light'absorbing substances, e. g.

aesculin, quinine, etc.. A Y

A still fur-ther modication of the-hydrocarbon copolymer element of this invention may be obtained by adding a small amount such as 0.1% to preferably 1 to 5% of a diolen such as isoprene into the mixture of styrene and isobutylene or other reactants being copolymerized. This dioleiin makes the-k resulting tripolymer slightly unsaturated, .having an iodine number rangingY from about 1 to 7,5, so thatA its -surface may becomev slightly harder upon later oxidation.4 This slight unsaturation Aalso' gives lthis resinous hydrocarbon plastic the ability to be vulcanized or cured by treatments somewhat similar to those used for vulcanizing ,a synthetic-rubber made by low temperature copolymerization of isobutylene in the presence of a small amount of a polyolen of 4 to ll2 carbonatoms such as 1 to 3% of isoprene or somewhat larger amount, e. g. 5 to 10% or so of butadiene. Y

The other primary element of the products and articles made according to this invention is a body, whichl may be either a thick mass or a thin film, of a polar plastic, such as referred 4to at the beginning of this specification. Typilulose, etc., any of which cellulosic materials may or may not be plasticized with suitable `materials known .to the art such 4as methyl phthalyl ethyl glycolate. Other types of polar plastics include phenol-formaldehyde vresins ,ofV various' types `known'to the art, urea formaldehyde plastics,

glycerol phthalic anhydride plastics,- polyvinyl acetate,V polyvinyl' chloride; polyvinyl alcohols, polyvinyl copolymers e. g. acetate-chloride, Poly- A vinylidene chloride, polyesters such as thosejmale Vby polymerization lof 1,2-hydroxy stearic,acid',gel-

atin, and polyamides such as those formed by ing agents,: antioxidants, etc.

The. above ,described two primary elements, namely the hydrocarbon copolymer and the polar plastic, may be brought into conjoint use in a number of different ways, such as by coating a body of one by a thin film of the other, applied either molten or dissolved in a volatile solvent which is .laterz evaporated, or by laminating one or more layers of each element together by sufficient heat andpressureV to bondthe plurality of layers together. vA further modification is to impregnate a fibrous material such as paper or cloth or' wood,`or even just coat; or vimpregnate one surface of such material with one element and thenfapplythe film or'sheet of the other elementtheret'o, either by heat sealing or by use of an intermediate-adhesive(layer.` Suitable adhesives for such purpose; include polybu.- tene suchas mentioned hereinbefore as a plasticizer, or some of the various natural or synthetic waxes'res'i n's,4 gums, etc., or 'even adhesive compositions comprising at least one of the two main elementseitherrdissolved in' or softened by a vvolatile solvent, orfsftened by a suitable plasticizer. ,Y

The laminated orfother conjoint products 0f this invention maybe u'sed' alone,jsuch asV for use as a flexible 4wrapping sheet material which is'moisture-proohtough, durable, and preferably Yalsoresistantfagainst. softening orv penetration by oils such las mineraloils or fatty oils. lFor instance, a colorless, transparent sheet offregenerated cellulose havingfa. thickness of lapproximatelyO-.Ol inch, or such a sheet containing a small amount of clear color such as a green dye, anorange dye, red dye, etc., may be laminated withv a thinsheetvor Afilm of stybutene, sc that tha-resultantlaminated sheet material makes a practically ideal transparent wrapping material, for instanatfor wrapping'food such vas butter, meat, bread, etc. or for wrapping dried foods which must be stored over along periodl of time and yet must not be permitted-toy absorb moisture, suchas dried bananasgdried chicken, meat, etc. vSuch a wrappingmaterial'may,also be used either int-,the Veryjhin, flexible form, or in a slightly-thicker and morerigid form for Ipackaging frozen foods, :particularly because this combination wrapping-material retains its'flexbility, moisture-proofness,- and l:other desirable characteristics evenpat temperatures substantiallybelovvfreezing:l In using such wrapping material, if-the substance to be'wrapped'is one containing a highv` proportion ofl water vor lhas van essentially non-fatty surface, .eitherfdryj or wet, it is best touse sthe stybutene side as the inside surface of the-wrapper coming in contactgwith the product being wrapped.; v Orl the ,other-hand,

- if the foodr or other product being wrappedfhas a surface .which is oily or lfatty innature the wrapper may be reversed so that the stybutene surface is on the outside and the regenerated cellulose surface is` onV the4 inside, becauseI fats andvfatty oils have a sufficient solubility in the stybutene copolymerithat such surfacefmay becomev unduly softened. An alternative modification, for use: in Wrapping materials of a fatty or oily nature-, isl to laminate; two, sheetsuof regenerated'cellulose with oneswinterrnediate sheet orv film of moisture-prooiing stybutenay--carv if only one sheet of regenerated celluloseisused, then the Y exposed surfacev of the stybuteneumay be :coated with athin .iilmof avolatile solvent solution 'of a `polar plastic in whichfatsj and/oils have no solvent action', such asyansolutiongof regenerated cellulose', -cell'ulose--acetate,. etc;` in amyl yacetate or a mixture thereof with ajketone,v

suchas. acetone,I methyl ethyl, ketone,`` etc. Y.

, In Vcase the colorless, transparent vsheet-material is not likely to come in Zcontact with mineral or fatty oils, a suitable modification lof the invention comprises a single sheet of regenerated cellulose having a thin film ofistybutene applied on each side thereof by passing a continuous sheetl of the regenerated cellulose through a` bath comprising essentiallya volatile solvent solution of the stybutene, e. gv.; a solutionl of stybutener having` anaverage molecular weight of about 60,000vanddissolvedin toluene..v Immanufac-turingv such a sheet material the volatilesolvent can, of course, be recovered `for re-use. "After the volatile solvent haslbeen'evaporated from such a coated sheetffit may, if desired, be passed through a bath in order to coatboth sides with a thin film of avolatile solvent solution of an loil-prooi' polar plastic such as regenerated cellulose,cellulose acetate, etc. v-

Prcducts made according to this invention have alarge number of advantagesoverproducts heretoioreY available,v because. the Ytwo primary elements of the present products have special characteristics, each not only serving its -own function in a separate way, but also in cooperation, in

ymany v.cases mutually protecting each] other against the. undesirable effect, vof moisture, oils, chemicals, light, heat, oxygen or otherdeteriorating influences. One ladvantage contributedr'particularly by the .stybutene element is its resistance to moisture yvapor penetration, Whichmay, lif desired, be even further improved by dissolving or otherwise compounding into the stybutene a small amount of wax or polybutene, etc., Another advantage is that stybutene and other cycalkene copolymers are much more resistant. to. depolymerization. or other deterioration `by ultraviolet light than other high, molecular weight polymerssuch as polybutene which are otherwise very suitable for use as an adhesive coating agent either alone or in conjunction'vvith materials such asV paraiin wax. Astillifurther advantage, which is ofA particular use when the products` of this invention are intended for use as electrical insulation mediums such as for insulating electric. wires, cables, etc., especially those carryinghighrvoltages, is that the cycalfkene copolymers are substantially resistant to gas formation when subjected to the influence of high voltage electricity suchas corona discharge, etc. For such electrical insulation purposes' the s tybutene layer or hlm can be still further improved byv havingdis- Asolved therein some lhigh molecular Weight polystyrene, which is compatible therewith,A even though it is not compatible with other high molecular 'weight hydrocarbon polymerssuch as polybul/ene.

' Other advantages accruing .from the-invention,

particularly when. the products, madeY are intended to be used as flexible wrapping materials, include the fact that the cycalkenecopolymer canl genmany polar plastic sheet` materials, such as regenerated cellulose, etc. On the other hand, the exceedinglyvsmooth, shny non-tacky surface of regenerated cellulose sheets rand other polar plastics is highly advantageous for coatingorrlaml .inatin'g Aon the surface, of stybutene, Iwhich .sometimestendsto soften in case' of frequent handling,

due to a slight` absorptionof oils from the lingers.

When laminated inoductsv are prepared, Such as for usey as wrapping paper, etc.,v thefedges may be fused or heat sealed together, or one particular layer may. be permitted to protrude beyond the other layers and then lapped over the other layers and bonded by hea-t sealing or byla suitable adhesive. ,A Laminated sheet. materials made accordingA to this invention may, if desired. be used alone, for instance, as a flexible Wrapping material: if very thin, i. e. having a thickness` of less'f..,thanv 0.005

inch v`and preferably not` more than about'fg0-002 inch, or' as a window,material,i. e.V a` glass sub,- sti-tutev if the products are used ill, suicient. thickness to give required rigidity,i. e- .atleast 0.01 inch for small sheets and at. least about 0.05 inch for larger sheets such as. 2 feet square Orvl'arger. For such use as windows, these. products vhave numerous advantages` over glass,vsuch Vas greater toughness with resultant low breakage costs, lighter weight which enables saving -in weight. in

regard to the window frames, greater transmission of ultraviolet-hghtwhich meansbetter health for humans and better plant. growtht in greenhouses and under skylights, and also these laminated plastic windowsl are suiciently flexible to permit making -curved Windows. .l I

The conjoint plastic products of this invention may also be used asa coating on a base which may be either flexible'orrigid, such as paper, cloth,

metal foil (suchasfor use-.as `thimflexible wrapping material or for makingthe laminationsl of an electricV condenser), or may be used as. electrical insulation 4such as spiral wrapping around an electrical wire or cable or it may be applied by extrusion or strip coating, or the lsuccessive layers may be applied from solution in avolatile solvent. These conjoint products may alsov be applied to wood, plywood, rigid plastics` such as molded articles, tile, etc. One 01' more successive layers may be sprayed molten or in volatile solvent solution on to the'base or they may bel applied thereto by heat sealing,y preferably Aunder pressure.

The laminated products of this invention, either used alone or in conjunction With one or more layers of flexiblek fibrous sheet materials such as paper or cloth, are also particularly adaptable for the construction of containers such asboxes, cans, tubes, collapsible tubes, such asffor tooth paste, paints, etc. When use in a clear, transparent condition Without any opaque materials such' as paper, cloth, etc they have a definite advantage over similar .articles made of metal foil, in that the transparency permitsl seeing the contentA of the container Withoutopening it. These products may also be used in the preparation of drug and vmedicine ampules, for instance, agelatin coated ampule which has a much greater resistance to moisture vapor penetration' than an ampule made of gelatinA alone. Similarly, ycapsules having a removable lid portion can be advantageously made lfor containing drugs, medicines, chemicals, foods, etc. in the form of powder, pills or tablets, etc. Bottle caps and other container closures can also be made of these component products.

Another novel use of the products of this invention is for the construction of humidostatl elements, namely, by the preparation of bi-plastic strips, having for instance one side made of Va cellulosic lm r sheet which is capable of absorbing moisture from the air and therefore ex'- pands and contracts according to the moisture Y content of the air, while the other side o fthe bi-plastic strip may be made of ajilm or sheet of stybutene which is not effected v by moisture changes in the air; such a bip-plastic strip will consequently bend in one direction or the other according to the changes in moisture content of the air and by making electrical contact when it bends in each direction, the instrument may be used to control equipment adapted to either increase or decrease the humidity content of the air as required. A

The objects and advantages of the invention will be better understood from aconsideration of the accompanying vdrawing in which Figure 1 represents a cross-section of Aa two-layer laminated product, Figures 2, 3 and 4 are cross-sections of three-layer laminated products with alternative arrangement of the layers, Figure 5 is a cross-section of a product similar to that shown in Figure 4, except with the addition of another layer.' Figures 6, 7 and 8 are cross-sections of still further alternative arrangements of three-layer laminated products, Figure 9 is a cross-section of a five-layer laminated product, Figures Y10 and 11 are enlarged cross-sections of a bi-plastic filament, with alternative arrangements of the two different plastic elements, Figure 12 is similar to Figure 11 except for the addition of a third outer layer, and Figure 1.3 is a longitudinal section of an insulatedy electrical conductor which part is cut away to show the construction. In all of these figures like reference numerals refer to like types of materials.

Referring to Figure 1, the reference numeral l indicates a layer of hydrocarbon plastic, by which f is meant a. hydrocarbon plastic of this invention, namely a cycalkene copolymer, e. g.l stybutene, and this is laminated to va polar plastic 2.

Figure 2 shows a laminated product in which a layerV of hydrocarbon plastic l is bonded with a polar plastic 2 by an intermediate bonding layer 3, which may, for instance, comprise an adhesive such as polyisobutylene, Vparaiin wax, or a mixture of the two, or othersuitable adhesive plastic compositions, such as those described hereinbefore.

Figure 3 shows a three-layer laminated product in which the middle layer 4 comprises a fibrous sheet material such as paper or cloth impregnated with a hydrocarbon plastic l, and this middle layer is coated on each side with a relatively thin lm of polar plastic 2.

In Figure 4, two exterior layers of polar-plastic 2 such as thin sheets of regenerated cellulose, are bonded with an intermediate layer of hydrocarbon plastics. e. g. stybutene. In Figure 5 the laminated product is identical with that in Figure 4 except for the further addition on vone side, of a thin filmA of a non-tacky ,water-proofing 111m 5. Y

v8 Figure 6 shows a middle layer of polar plastic, such as a thin sheet of regenerated cellulose or of cellulose acetate, etc.,'coated on each side with a thin film of i hydrocarbon plastic, e. g. stybutene. Figure '7 shows a thin sheet of metal 'foil 6 bonded vwith a thin layer of hydrocarbon plastic I, e. g.

stybutene,` to an outer layer 2 of polar plastic.

Figure 8 is identical with Figure 4 except that the two outer layers of lpolar plastic 2 and 2' are shown to'be made of two different polar plas'tic materials;-for instance, the upper layer of polar plastic 2 may bea thin sheet of regenerated cellulose while thelower layer of polar'plastic 2" may be a thin sheet or film of'gelatin'.

Figure 9 shows a centrallayer of metal foil 6 bonded on each side by a thin layer of hydrocarbon plastic Al to an-,outer layer of polar plastic 2.

Figure 10 shows a cross-section of a bi-plastic filament, greatly enlarged, in which the central portion or core is an extruded or drawn lament of hydrocarbon plastic l, While the cylindrical instance a thickness of 0.001 inch which may be coated'by dipping into a volatile solvent'solution Vof polar Vplastic 2, such as a solution of regenerated cellulose or cellulose acetate and the like.

Such a lament or a thread composed of a plurality of such filaments, maybe used for weaving into cloth,` and used for instance in making stockings, socks, or other articles of clothing such as suits, dresses, shirts, underwear, raincoats, etc., as well as tent fabric,l flexible automobile tops, etc.

`Figure 11 shows a cross-section of a bi-plastic filament having a construction the reverse of that shown in Figure 10, namely that in this case the central portion or core composed of a polar plastic, which may for instance be the filament of cellulose acetate or of a polyamide such as that marketed under the trade name Nylon, having aY thin outer coating of al hydrocarbon plastic I which vmay for instance comprise a stybutene,

'preferably having a combined styrene content of at least 50 or 60%, if desired, modified by having dissolved therein a small amount of polystyrene, or paran wax, high molecular weight polyisobutylene, etc., to prevent this outer film from l being or becoming tacky.

Figure 12 shows an enlarged cross-section of a composite plastic filament similar to that shown in Figure 11 except that it also comprises a third or outer film of polar plastic 2 or 2', indicating that this outer film of polar plastic may either be composed of the same material as the central or core portion of polar plastic 2, or it may be of adifferent type of polar plastic. For instance, this three-layer filament may comprise a strong central portion or core of polyamide such as nylon, coated first with a thin film of stybutene to make it resistant to water or moisture, and finally an outer film of polar plastic such as cellulose acetate. These two middle and outer layers may be applied by passing the central core filament through a bath of volatile solvent solution of stybutene first and then through a bath of Vvolatile solvent solution of cellulose acetate, permitting the solvent to evaporate after each dipi '.9 n sion, spiral wrapping orany'of the other methods :mentioned heretoforerom ikncwn to .theartand 'then-with a"layerbf-fpolargplastic 2 .suchas yregenerated cellulose which-maybe;lappied'fby spiral wrapping or any o f the othermethods mentioned heretofore or known `tti-the art, and then with a laye? f "DQalDlaStQ i2 Sdlffli .Tegenerated 991111- f'lQS@ 1611110.11 Ina-rabe applied yby ispira-l wrapping, .or a-celluloseacetatewhich-maybe applied by .p assingfthe coatedqconductor fthrough .a bath `of volatile solvent solution vof lcellulose acetate, then after` complete evaporationpf the-solvent (if fsuch jwasused? -applying alayer; o f rubber. suitably by extrusion, after which itis preferably vulcanized and finally given the usual outer covering of braid. Such an electrical `conductor has several unexpected .advantages over; products used heretofore, -beeause the-layer @ffsiybutene .is ca -pure homo.- fge'neous .hydrocarbon andinas excel-lent electrical resistant propertiesfand -bondsvery rmlyto the .metal.conductor t, and ha particularlywhen Ycomposed of a relatively highpr-OPQlOn-'of cyclic constituents, e. g. a stybutene having at least 50 or 60% of combined styrene content, sufcient .resistance to cold owthat rthe electrical conduc- `V1;"or'iv-ill .not shf-t radiallyltlrfough the -li-ydrocarbo'n plastic, as' is .one disadvantage .ofsome softer types of hydrocarbon plastics used heretofore. Another advantage is. that the layer of stybutene bonds excellently with the next layer of polar plastic, such as regenerated cellulose, and there- 1fore'prevents"longitudinalslipping of such lregenerated cellulose' l'in respect -t'o the metal'coductor 6 during the manufacture of such insulated vconductor. Also, the .stybutene is quite resistant to breakdown under the influence of high voltage` relectricity, andtherefore -isadvantageously placed immediately fin lContact* with Ythe electrical con- `.duc'tor 6 this immediate direct 'Contact 'with the metal is also advantageous because the stybutene isaa Lpure saturated hydrocarbon Aand Ahaslno tendienc'y` vto cause =or .permit oxidation Yorl corrosion for? the metal conductor, whereas if-anunsaturated hydrocarbon material such VVasy `'rubber f-is placed v-irnmediat'ely next Ito-the electrica-'licenducton particularly-'one made -o'i' copper,` oxygen lreadily absorbed by the -rlilziberand then'transmitted to the conductor and .causesorrosiom apparently the copper having some accelerating influence on the .oxidation ofzthe rubber.' r

Enfadditionto :the :examples described above yin reference .-.to t'heldrawin'g; the ifollowing v'additional 'ecamples'will sfu'rther .illustrate 1 the Iobjects and advantages of fthe-invention.' 1

.. c. Example 1" i l A. thin, jcolorless, utransparent sheet.` of .regenerated cellulose having a thickness ofabout 0.001 inch was coated witha thin lm of a solution containing about 10 to 15% by Weight of a stybutene of 50% rcombinedastyrene'gcontent and made-at' 103 afdissol-vedina volatile aromatic 'solvent-comprising 'a' maj or proportion .of toluene. "The r*solvent rwas, -evaporated,leaving 'a thin, lmoisture-proofhydrocarbon copolymer'coating on the regenerated cellulose.l A y vsheet of, stybutene Lof 50%" .combined styrene i contentland made 'at fi-L03@ which sheet was tough; Ilexible', .andnon-tacky and .had a thickmatic solvent as described"in"E ample 1. After thickness '0i' about 0.001- incluis coated on ione ll() partial evaporation' of the-"solverrtL jarrdlw'hile the surface was still stickyfathin," colorless, transparent sheet of regenerated cellulose having a thickness of about 0.1)0l`inch was pressed on to ythe sheet of the1 stybutene. The resultant laminated. sheet. material" ,was :'iiery; suitable i. for :use

' Av :sheet of regenerated cellulose Vand .a sheet fof stybutenewerelooth softened on one side with vvmethyl isobutylfketbnef and thenthe ltwo' softened surfaces were bonded togetherlbypres'sing. -After eventual evaporation of the residual volatile solvent, the resultantlaminated product was found .to be very .firmly bonded together. Tensile tests by rthe use .of the .'.IhwingResear-chealing Tester indicated a' bondistre'ngfth `at room'temperature oi ltldynes per? square inches. l

y K Example 4 kA sheet of plasticizled l.polyrnerized vinylidene l.chloridetivascoated `with k1,2% toluene .solutionof stybuteneshauing -a-coznbined styrene-content -of .about '101% anmmfade ,ioao The resultant product was a clear, colorlessfntransparent sheet material having extremely -loW- moisture vapor penetration, good tear resistance, and good flexibility. Similarly ,such a sheet of polymerized vinylidene chloride can be coated on both sides with st ybutene, andalternatively two thin y'sheets of polymerizedvinylidenefchloride may be'bonded together lwith -a thi-n fadhesive layer of stybutene .Example :5" i.: Athin sheet of jregeneratedjcellulose having a sidefwith a Volatile solventso'lution of vcellulose acetate, and after evaporation vof the solvent, is

further coated ori-fthe l saine jside with a .volatile solventsolution ofystybutene, similar tothe solultion lused in Example-1. Good Yresults arefalso obtained by applying a sheet'offthin"stybutene to the'coated regenerated cellulose, instead of applying a volatile solvent solution and stybutene; .this :.can' best' Joe .done zby 'bonding' the .sheets Vto- -g'ether under .pressurerj-.ust frbegfore )evaporation lof the lastV Ytracesv .of fthe-volatile solvent from the cellulose acetate film. i y Example 6 Two 'colorless transparent `sheets ofregener- .ated cellulose. havingafthiclkness .of about .0,001

inch are bonded'togethergby an'nterrnediate Ithin .of `s tybutene.havingY anaverage molecular Aweight the bondng... '.Good l.results .can also :be obtained by compounding small le'tr'nunts'ofr parailin-wax and/or high molecular weight polybutene with the stybutene whensef foliihlls bonding, W

layers of. cellulose acetate.

l I f Example 48 .Two colorless; transparent sheets of regenerated cellulose. having a thicknessiof about 0.001 inchV are bonded together by an intermediate thin sheet of stybutene having Van average molecular weight of about 60,000, using heat and pressure to Veiectthe bonding. Good results can ,also be Example 9 A thin sheet of cellulose acetate is coated with a thin film of stybutene having an average molecular weight of about 80,000 and having a combined styrene content of about 50% by heat sealing the two thin sheets together, and then the stybutene surface is coated with a thin lm of a toluene solution of polystyrene. After evaporation of the solvent, a hard non-tacky polystyrene surface is left on one side to protect the stybutene from contact with mineralor fatty oils, -while Y the stybutene'greatly increases the moisture resistance of the cellulose acetate.

Example 10 A thin sheet of regenerated cellulose having a thickness of about 0.001.1nch is coated with a thin film of a volatile solvent solution, i. e. a naphtha solution, of a polybutene having an average molecular weight of about 80,000, and after evaporaltion of the naphtha, a thin sheet of stybutene having a combined styrene content of about 60% and made Fat -l03 C., is applied to the polybutene surface with pressure in order to obtain a rm bond between theregenerated cellulose and the stybutene. A sheet of cellulose acetate can be used in place of the regenerated cellulose in such a'laminated product.

Y Example 11 A thinsheet of regenerated cellulose is bonded .to a thin sheet of plasticized polymerized vinylidene chloride by an' intermediate Vbonding layer of stybutene.

Example 12 tion of a phenol formaldehyde resin. Similarly,

a urea formaldehyde resin can be used in place of the phenol formaldehyde resin.

Example 1.3

Two thin sheets of .plasticized vinyl acetate-v Example 14 Two thin sheets of polyamide plastics marketed under the trade name Nylon are bonded together rwith a thin. adhesive, moisture-proof film of stybutene.

i.. Exam??? 15,; V.Example 14 is duplicatedl except that a thin sheet ofiregenerated celluloseis used in place of one of the sheets of polyamide Example 16 A sheet of-regenerated cellulose having a thickness of about 0.001 inchis coated with a thin volatile solvent solution offstybutene, such as used in Example 1, and after evaporationof the solvent is laminated by heat sealing with a lsheet of aluminum foil having athickness oi.' .0002 inch, using the stybutene to bond the aluminum foil to the regenerated cellulose.

v Example 17 Example 16 is duplicated except that a small amount of polybutene, e. g. 5% of polymer having an average molecular weight of about 80,000 is added to the Volatilesolvent solution of the stybutene before application to the surface of the regenerated cellulose.

Example 18 Example 17 is duplicated except that a sheet of plasticized polymerized vinylidene chloride is used in place of the sheet of regenerated cellulose.

l Example 19 Example 18 is duplicated except that the aluminum foil is coated on both sides with the polymerized vinylidene chloride using the hydrocarbon adhesive as bonding agent.

' Example 20 Example 521 A thin sheet of stybutene having a combined styrene content of 50% and made at 103 C. is coated on each side .with av volatile solvent solution of chlorinated cyclicized rubber, the lm of the latter being onlyiof vsufficient thickness to impart a smooth, hard, non-tacky surface to the stybutene, while the middle layer of stybutene imparts strength, toughness and flexibility to this laminated product.

Example 22 Example 21 is duplicated except that instead of using a sheet of stybutene per se, a thin sheet of silk is used which has been impregnated and coated with stybutene to make a completely water-proof and moisture-proof cloth.

Example 23 by weight of a stybutene having a combined styrene content of about 60% and made at 103 C., is homogeneously compounded with 20% by weight of polyethylene having an average Vmolecular weight of about 30,000 by hot milling,

and then calendered in a thin film between two sheets yof regenerated cellulose having a thickness of labout 0.001 inch. v,

13 Example 24 A thin sheet of regenerated celullose having a thickness of about 0.001 inch is laminated by heat and pressure with a thin sheet of polyethylene likewise having a thickness of about 0.001 inch, by using an intermediate bonding layer, just thick enough to give good bonding, of a stybutene having a combined styrene content oi about 40% and made at -103 C. The stybutene gives a much better bonding between the polyethylene and the regenerated cellulose than these two materials would have without the intermediate stybutene.

It is not intended that this invention be limited to specic materials and modifications which have been given merely for the sake of illustration, but only by the appended claims in which it is intended to claim all novelty inherent in the invention as well as all modications coming within the scope and spirit of the invention.

It is claimed:

1. Laminated sheet material consisting of two sheets of regenerated cellulose with an intermediate layer of a styrene-isobutylene copolymer having an intrinsic viscosity above 0.6 and a combined styrene content of about 50 to 70%.

2. Laminated sheet material having a thickness of not more than about .002 inch consisting of one sheet of regenerated cellulose coated on one side with a film of a styrene-isobutylene copolymer having an intrinsic viscosity above 0.6 and a combined styrene content oi about 50 to 3. A flexible, foldable, moisture-proof transparent laminated sheet material consisting o! a layer of regenerated cellulose having a thickness of about .001 inch and a layer of styreneisobutylene copolymer having an intrinsic viscosity above 0.6 and a combined styrene content of about to 70%.

4. A laminated sheet material comprising a thick layer of regenerated cellulose and at least one thin film comprising a styrene-isobutylene copolymer having an intrinsic viscosity above 0.6 and a combined styrene content of about 50 to OBER C. SLO'ITERBECK. WILLIAM H. SMYERS. DAVID W. YOUNG.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date Y2,061,934 Mueller- Conradi et al. Nov. 24, 1936 2,175,672 Scott et al. Oct. 10, 1939 2,213,423 Wiezevich (Gaylor) Sept. 3, 1940 2,270,285 Frolich Jan. 20, 1942 2,274,749 Smyers Mar. 3, 1942 2,278,515 Gibb Apr. 7, 1942 2,300,072 Smyers Oct. 27, 1942 2,356,290 Wendler Aug. 22, 1944 2,369,471 Latham Feb. 13, 1945 2,396,293 Smith Mar. 12, 1946 2,434,662 Latham et al Jan. 10, 1948 FOREIGN PATENTS Number Country Date 507,323 Great Britain June 9, 1939 

1. LAMINATED SHEET MATERIAL CONSISTING OF TWO SHEETS OF REGENERATED CELLULOSE WITH AN INTERMEDIATE LAYER OF A STYRENE-ISOBUTYLENE COPOLYMER HAVING AN INTRINSIC VISCOSITY ABOVE 0.6 AND A COMBINED STYRENE CONTENT OF ABOUT 50 TO 70%. 